This article is from the source 'bbc' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at https://www.bbc.co.uk/news/uk-50941114

The article has changed 2 times. There is an RSS feed of changes available.

Version 0 Version 1
UK weather: Why was it so warm on Saturday night? UK weather: Why was it so warm on Saturday night?
(about 1 hour later)
Temperatures reached 16.8C in northern Scotland overnight - the highest ever recorded for the UK this late in the year.Temperatures reached 16.8C in northern Scotland overnight - the highest ever recorded for the UK this late in the year.
The figure, recorded by the Met Office, in Cassley, Sutherland at 03:00 GMT on Sunday, is the highest on record for 29, 30 or 31 December.The figure, recorded by the Met Office, in Cassley, Sutherland at 03:00 GMT on Sunday, is the highest on record for 29, 30 or 31 December.
Northern Wales and north-east England were also unseasonably warm.Northern Wales and north-east England were also unseasonably warm.
Forecasters said the "remarkable" overnight temperatures were down to a phenomenon called the Foehn Effect.Forecasters said the "remarkable" overnight temperatures were down to a phenomenon called the Foehn Effect.
This happens when moisture-laden air, carried on south-westerly winds, travels over high ground. This pattern develops in mountainous regions, such as the Scottish Highlands, and results in wet and cold conditions on one side of a mountain and warmer and drier conditions on the other.
As the humid air is forced to rise up over the western side of the mountain, the air cools and condenses, forming cloud and rain. It occurs when moisture-laden, high humidity air is pushed over high ground by strong winds. As it rises, the air cools and condenses, forming cloud and rain.
Rain falls on the top or the windward side of the mountain but the eastern side is much drier. Dry air warms up more quickly than moist air so as the air descends it warms up significantly. Dry air then travels down the other side of the mountain, picking up heat as it goes and resulting in higher temperatures at ground level.
In the UK, this effect is commonly seen in eastern Scotland, north-east Wales and north-east England.In the UK, this effect is commonly seen in eastern Scotland, north-east Wales and north-east England.
Other parts of the UK also saw unusually high temperatures overnight. For example, temperatures of 13.3C were recorded in Chillingham Barns, Northumberland and 11.5C in Rhyl, north Wales.Other parts of the UK also saw unusually high temperatures overnight. For example, temperatures of 13.3C were recorded in Chillingham Barns, Northumberland and 11.5C in Rhyl, north Wales.
Alex Burkill, a meteorologist for the Met Office, said it was highly unusual to reach such high temperatures overnight in December.Alex Burkill, a meteorologist for the Met Office, said it was highly unusual to reach such high temperatures overnight in December.
"Getting temperatures of 16 or 17 degrees in December isn't all that unusual but it's remarkable that this was during the night," he told the BBC."Getting temperatures of 16 or 17 degrees in December isn't all that unusual but it's remarkable that this was during the night," he told the BBC.
The current record for the highest daily maximum temperature in December in the UK is 18.3C, recorded in Achnashellach in the Scottish Highlands on 2 December 1948. However, this was recorded during the day.The current record for the highest daily maximum temperature in December in the UK is 18.3C, recorded in Achnashellach in the Scottish Highlands on 2 December 1948. However, this was recorded during the day.